infodumping

Infodumping is delivering a large amount of information all at once, often more than the listener wants or needs.

The term originated in fiction writing, where clumsy exposition bogs down narrative: The first chapter was just infodumping about the world's history.

It now applies to conversation, where someone unloads specialized knowledge without reading social cues: He started infodumping about train schedules and couldn't stop.

Common in discussions of autism and ADHD, where infodumping about passionate interests is recognized as a trait rather than a flaw.