Why did a game just randomly end in a draw?

I was never requested for a draw and would definitely not have accepted. I was going to win as he only had his king left. he could still move to plenty of spots too. so I do not understand why it randomly completed with a draw?

Things the computer does are very rarely random.  Did you & he repeat the same moves 3x in a row? 

If it's this game, http://www.chess.com/echess/game?id=85217472 , it's marked as "insufficient material".  If I understand correctly, that means neither side has enough pieces to force a checkmate.  As you had only the bishop left, I'm almost certain that's true.

What game is this? What is the ending position?

@sepanak It's possible your opponent claimed a draw if this is the case.

Article 9.6 of the Fide Laws of Chess.

If this is indeed the game you're talking about, then you were very lucky to get a draw.

How this can be a draw?

@hungrymozzy It's a stalemate. The black king is not directly in check but has no legal moves, so the game ends.