Your opponent (who should be unnamed when posting games to this forum) was trying whatever legal means possible for a win with a worst case of draw by perpetual check.
Do you remember the time control situation for both of you towards the end of the game?
Here's how I would see this from your opponent's side:
1) Either I can force a draw by perpetual check
2) Or he screws up with a mistake trying to stop these frustrating checks.
Assuming your rating is an accurate reflection of your playing strength, I don't think mistakes are out of the realm of possibility for both of you.
So what happened? You didn't fall for 2) so 1) occurred.
This is frankly a practical way to play in most positions that "look" drawn but are not dead drawn, especially when the time control situations are iffy and you have queens on the board with additional pieces.

You know the game is going for a draw, but just for the sake of frustrating people.... keeping continous check is horrible.... check the final stages of the game.