The contact owns a 2008 Chevrolet HHR. The contact stated while warming up the vehicle, the rear window exploded without warning or impact. There was smoke coming from the front of the vehicle. There was an abnormal burning odor detected. The contact called the local dealer, but the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 56,000. The VIN was not available.