How do you capture context from browser research sessions?

Curious how people here handle this: you're researching something, you have 20-40 tabs open, and there's a lot of implicit context in your head, why you opened each tab, what you were comparing, what matters. Then you close the session and that context is gone. Bookmarks don't capture why something mattered. Notes require active effort mid-research. What systems do people use to preserve that context?