Why does sometimes things zoom out whenever I stare at them for too long?

This happened multiple times but whenever I am in class and is listening to the teacher and staring at her for a really long time. She suddenly just zooms out and it looks like she’s really far away. I don’t know what’s going on why my eyes doing that. It gets back to normal after a pretty short amount of time. Does anybody know anything like this? (I tried searching it up and no its not alive in borderland syndrome 😭)