I just had the same eperience in Florida in my 2006 XB. I was standing in the parking of a Hardees talking with my grandaughter and it just exploded. Really weird because I had just been telling about an asteroid hitting the earth. and 10 minutes later this happened. Really strange.Today my rear window shattered, i.e., exploded. While sitting in the sun in a parking lot the rear window shattered with enough force to send glass to the back of the front seat and several feet to the rear and sides of the car. The glass still in place in the upper right corner showed stress lines in a radial pattern from a point at the corner of framing. I think the glass was in contact with the metal trim and our current 90+ temp's in MD put enough stress to shatter the window. Suggest you run a feeler gauge around the inside surface to see if this is a common condition.
The fact that it shattered with such force suggests that it is locked/glued in a fixed position so that it is stressed in hot conditions. Of course there is the added possibility that my particular window had a defect that caused the failure.
Curious if any others have had this experience. Did a site search with no results.
Currently at the dealer being assessed for warranty repair. [2009 model, 2 months old, 2004 miles]