I'm nearly 17 and for many years, sudden thoughts or ideas pop into my head just before they happen.
When it happens, it's not like a vision or a daydream like other users have described on this site, but more of a sudden idea or phrase.
The first time it happened it was a vision- a picture in my head. My parents were taking me somewhere and they wanted it to be a surprise and wouldn't tell me were we were going, and a picture of a sign suddenly popped into my head and I told them were we were going. I thought that I must have been half day dreaming and I actually saw the sign on the way, but on the way back there was no sign there. That's the first and only vision I have ever had.
Other experiences have been words or phrases suddenly coming to mind, like knowing what someone is going to say before they say it (which is totally unrelated to our past conversation), or what happened the other night- we were watching a quiz show on tv, and the answer popped into my head before they asked the totally random question. Others have been knowing what song is going to play next when my music player is on shuffle and there are thousands of songs, and who is about to sign in on my instant messenger, where I have other 600 contacts.
I haven't been able to come up with an explanation for this happening when it does, which is why I searched for a site like this so I could explain my experiences and possibly find out how to use it, if I could maybe increase the chances of it happening or possibly make visions happen rather than just knowing a few words before they are spoken?