Could be a scene that has shocked you to your core, filled you with pure elation, even had some sort of connotation to a part of your life. To kick it off, obvious but good examples of what I'm thinking.
The ending sequence from Oldboy.
The moment Amelie reunites the man with his childhood trinkets.
When the newly appointed civil worker overlooks Ikiru's park he'd worked for.
The dream sequence from Shutter island