Was driving for 25 minutes in the truck. Temperature outside was around 40 degrees Fahrenheit. I did not know the rear defroster was on. My son who was in the back seat smelled smoke and said that the truck was on fire. I pulled to the side of the road and looked in the back and could see the rear defroster on drivers side was glowing and emitting smoke. I looked at rear defrost light and it was on. I turned the rear defroster off to prevent any more current from going through the wire. Once we were sure there was no more smoke or fire we got back in the vehicle. About 300 seconds later the window shattered. If my son was not in the back seat and smelled smoke the back seat could have caught on fire. I called the dealer and they stated no recalls for my vehicle. There is an article from Canada describing what happened to my truck. https://gmauthority.com/blog/2019/07/gm-truck-recall-2014-2019-silverado-sierra-trucks-over-fire-risk/ No warning at all. The rear defroster just started smoldering and smoking. I do have a rear sliding window so only the left glass pane was impacted.