You have to be careful to make sure the bead of the tire is seated properly in the rim. Most tires have a witness line that should be even around the tire, the same distance above the rim.

If it is higher somewhere, that is likely to bulge more. The tube can slip out between the rim and the tire, and pop.

That happened to me a few times, before I caught on. Most often it was after I pumped up the tires but wasn't going for a ride.