Likely the tube was caught between the tire and the rim - partially inflate the tube before installing it, not using levers for installation and going around the wheel after the tire is installed pressing the tire in and confirming the tube isn't pinched between the tire bead and rim will help to prevent this. If you have a small sidewall cut in the tire a very similar thing can happen - check the tire in the area where the tube exploded for any small cuts.

PS, was that the gunshot like sound I heard at 9:10 this evening?