Generally when people have odd, unexplainable page breaks I refer them to two areas where they often find the root of their problem:
Text Wrap
and
Keep Options
If there are graphic elements at/near the spot where a funky page break occurs, I recommend opening the Text Wrap panel, then using the Selection/Black Arrow tool to select graphics and InDesign-created elements and frames in the area of the unexpected page break. Very often one of those elements/frames has an unexpected text wrap setting which is throwing the text flow off the existing page and onto the next one. Don't forget to check Master Page Items if you've placed them in your document. You can't select them without extra effort on the document pages, but when you go to the applicable master page(s) those offending elements can be detected.
If you find any elements with an unexpected text wrap, turn the text wrap off and see if the text flows as you expect it to.
For text-based funky breaks, they generally come from odd Keep Options set in the Paragraph Style options box. Get your Text tool and place your cursor into the block of text before the page break, then open the Paragraph Styles panel and see which style, if any, has been applied to the paragraph. Pay special attention to whether the style shows a plus (+) sign after the style in the panel, which will show custom formatting has been applied to the paragraph. Go to the flyaway menu — the spot where three horizontal lines are in the upper-right of the panel, and select the Style Options... menu command to open the Paragraph Style Options box. On the left side, select the Keep Options box in the menu. Make sure that the Keep check boxes are not selected, and that the Paragraph: options box is set to Start Anywhere. Now click in the first line on the following page and do the same thing. Any settings in the Keep Options section can cause unpredictable results.
I'd say in the vast majority of cases, unpredictable page breaks are due to one of these two factors — like 95%+ of the time. If these are not a factor, plese share some screen shots of where you're getting strange results and we'll do our best to help you.
Hope this helps,
Randy