My theory is hyper activity in our brains ability to predict the future.
We predict things unconsciously all the time, and these assumptions make our life easy. Things like our next step being on solid ground, land marks being exactly around the corner we turn, peoples moods in advance of the actions we take... our brain does a lot of subconscious predicting to keep our full capacity thoughts undisturbed.
I think at some point, maybe in dream states, we predict extremely far into the future, and then the prediction gets buried and overlaps when the predicted event happens. This also means we have a lot of wasted memory for when these pedictions don't occur, but we dont realize it because it never happens for that second time.
... my other theory is that our soul or spirit, or what ever body our hyper reality selves inhabit travels to the future and gets pulled back unconsciously keeping track of what happened.