Seems to usually be from hitting the rev limiter, causing sudden drop in manifold pressure from boost to vacuum. One side of the diaphragm is exposed to intake manifold. The greater your boost, the greater the absolute change in pressure when you hit limiter or snap the throttle shut. Can happen without abusing the car, too. Newer unit seems more reliable than older one, according to posts here.

 

Frps

Always keep a spare in the glove compartment. If you've got a parts connection they are about $40...cheap insurance. It can strand you real quick.