I've never heard of one to just break open all of a sudden, although the possibility is there. There's a couple of things that could cause it. Weak glass, old sealant, not being level to name a few. Not a full blown break, but one did fracture and leak at the T-Rex Restaraunt in Disney, Orlando.
http://www.foxnews.com/leisure/2014/03/18/giant-fish-tank-bursts-open-at-downtown-disney-restaurant/
Sent from my iPhone using Aquarium advice.