Car window exploded!

Closing the door on my citreon c2 on Saturday last and my car keys hit off the back passenger window whereupon it literally explode inwards. Although the car had been in the sun earlier, I had at this point just driven it over 10 miles from my home so it was not overheated at this stage. Anyone heard of this before? Is this a fault in the glass?

same thing happened to me a couple of years ago. the guy who replaced the windscreen said it was more common than you would think, and its usually caused by high pressure, but more commonly in winter when mine happened. When it happened both myself and my friend slammed our car doors shut at the same time, and it just popped. On expensive sporty cars you may notice that the windows lower slightly when the car is stopped and the door opened, and then close again once the car door has been closed - this is to stop this exact thing happening.