Carl Jung states in his theory of the human subconscious, that it holds hints about the future and past. He explains it kinda this way:
There is a part of the suconscious which is inheritable, it is something like the merging memory of all humans who have lived before you. As years gone by, your subconscious has filtered events which happened to all your Anchestors in some way. And since dreams are connected to the subconscious, it would technically be possible to dream about the future.

That sounds crazy right now, so I'll give an example.
The majority of your anchestors would have experienced their parents dying. So I guess when you are at a certain age, your subconscious might suggest you that your parents will die in the near future. (Not that it really is going to happen, it simply states that it normally happens at this age.)

Of course it's nothing like future telling, it's only patterns of possible events which are suggested.

Another way to have future related dreams would be, that your subconscious mind has realized something before you consciously noticed it, and tries to tell you about it in your dream. Let's say you dream about coming too late to school. The exact day you really come to late, but this could've happened because the day before you subconsciously noticed a paper which stated that the train you usually ride with won't be availiable tomorrow.