It depends on the kind of comic, but usually for stories it's typical for a chapter to end before the start of a new concept. For instance, a shorter story the second chapter or so is usually the start of the plot developing, so the first chapter will be about introducing the main character and establishing a plot, and the next chapter is simply the continuation of the plot once it's been established. A longer story might have a few more chapters to establish the plot before getting to the meaty part where the plot progresses. Here's an analogy.
This is a story about a lab mouse trying to find maze cheese.
The first chapter is about the mouse. Where does he live and what is his environment like? Maybe he's suddenly picked up and placed in the maze, and I'd end the chapter with a sneaky cliffhanger.
The second chapter is about the new environment, and how the mouse reacts to it. Does he hide? Does he get lost in the maze and freak out for a few pages? Can he smell the cheese, or is he lost? Maybe he finds a friend mouse, and the friend mouse also smells the cheese, and they decide to find it.
The third chapter is about the journey to the cheese. Journeys are big chapters, but can be split into smaller ones. How do the mice work with one another? Do they get frustrated with each other about where to go? Do they have a falling out and split up to find the cheese on their own? Maybe a new danger is introduced, like trap cocaine cheese. Which one will find it first, and will they know not to eat it? Maybe one of them starts freaking out on cocaine alone and lost and starts making mouse crying noises. Maybe the other mouse hears them and tries to find them. They're so relieved that for a moment they don't even think about hating each other.
The fourth chapter: Maybe the mice have decided to put their differences aside and go back to finding cheese together, and so off the go, working together to navigate the maze. They run around for hours and hours and start to get hungry, but they can't find the cheese. They feel like they've gone through the whole mace twice over, but there's no cheese. Maybe they start to think there is no cheese, which makes them panic and start questioning everything. Then they start questioning each other. Did the other eat the cheese and lie? Was the cocaine cheese the real cheese? Even if they can smell the cheese, maybe it's a trick! So many questions. Once again they take their frustration out on each other, and decide to fite2dadeth.
Aaaand climax. Mouse battle. All their frustration and fear and panic comes out as they squeak and bounce around. They jump and bite and scratch or whatever mice do. But then one of the mice is strick in the heart and he DIEZ. It's over.Feels time. Survivor mouse feels the feels, knowing he's done something awful. Survivor mouse regrets everything, and cares about nothing anymore. He's all alone now.
Resolve: Survivor mouse is suddenly picked up and placed back in his home. There is cheese in the corner, glowing in all its glory. More mouse feels. Does he want to eat the cheese, after everything he's been through? Survivor mouse can't go back and change things now. He doesn't know why this is happening, but it's all over. He has the cheese. He remembers friend mouse and decides to eat the cheese out of..... LOVE???
Mouse adventures could end here, or you could keep going and get even deeper. Maybe friend mouse isn't dead, or maybe there was no friend mouse at all. Maybe there's bigger twist yet to be seen. You decide, next time, on Mouse Adventures.
So basically each chapter introduces a new scenario in response to the plot progressing. Mouse in cage. Mouse put in maze, finds friend and establishes goal. Mice work towards goal, sub-plot is introduced between mice. Sub-plot resolves, mice are inches from their goal. Sudden turn of events, intense things happen. Intense things finish, but the outcome was not as planned. Mouse returns home, where nothing will be the same anymore and mouse is not the same mouse as he was before. It doesn't matter how long the chapters are (especially if it's the meaty plot part), as long as they make sense in transition. Try breaking the story down in short sentences and see which parts look like they belong together and which ones stand on their own.