That is Deja vu.
It's a phenomenon that we are not even close to understanding.
The way I see it, since we only use 10% of our brains, the other 90% must have amazing powers, such as seeing the future etc..
I think when we dream we tap into that power and somehow get random glimpses.
You do dream, you just forget your dreams.
A healthy human being dreams more than 3 times a night.