What Causes Air to come out of a jug?

What happen was I had a big empty jum of water. The heater was on high and I had music blasting (I have b system). Well I started feeling this cool air. I was checking every making sure there were no windows open. Then when I was about to get the jug, I felt the air come out. I turned off the music it was gone and then turn music on there it was again. What caused air to come out of the jug? I probably learned this in middle school but I cant remember.