Rules for "draw" games

My opponent's clock reached 0:00, but the game was declared a draw -- why?  Was he somehow able to manipulate this?

My only remaining piece was my King.  However, the draw was declared 5 moves after losing my last other piece.

Lack of mating materials - king and two knights, king and a bishop, king and a knight!

The other rules for draw are - draw by three-fold repetition draw by perpetual checks draw by agreement draw by fifty-rule method where in a chess match if there are consecutive 50 moves without a pawn move and without a piece capture, it is declared a draw. Last one is my favorite - STALEMATE!! So, totally there are only six ways to draw a chess game!

I've been 'winning on time', but the game was declared a draw -even though my opponent still had his queen and lots more...! 

After you lost your last piece your opponent must have hadsufficient material to mate you, but you couldn't mate them.

When they ran out of time it was a draw.

If I was in a better position, more material etc. but din't believe I could mate my oponent in the emaining time I would try to take all of their (non-King) material in order to at least get a draw.

Yes, but why wasn't I 'awarded' with the win (on time) then? Sorry for being slow here...! 

You didn't win because you had no possibility of checkmating your opponent with just a King.

If you had one pawn left you would have won on time - even if you couldn't deliver checkmate with the pawn you could hypothetically promote it to a Queen or a Rook .

Perpetual check is not a draw unless it produces a repetition of position (three-fold) or a draw by the 50 move rule. Even then, the draw is not automatic. Rather, a player must claim the draw.

In FIDE events, the arbiter will enforce a draw after 75 moves without a pawn move or capture. 

Thanks to all for the responses.  The mystery has been clarified.

Thanks for clearing this out! Best thread ever...