I had this problem, I must've blown at least 6 tubes.
I'd be riding and it would sound like a gun shot. Sometimes at the beginning of a ride. Othertimes in the middle of a ride.
But the freakiest thing was having them explode at 2:00AM while the bike was sitting in our back hall.
The only common denominator was the new Specialized S-Works Mondos I had recently installed.
LBS told me no way, those were top of the line and no one had ever had a problem with them, but they agreed to sell me a couple more for cost.
Same problem continued happening - I checked the internet and found that others were having the same problem with these tires, but the shop still said no way.
In the end they gave me a pair of P3Rs and in the 3 years that have passed have never had a problem with exploding tubes.