I TURNED ON THE REAR DEFROST TO THE VEHICLE. WITHIN ABOUT 30 SECONDS, I SAW SMOKE RISING FROM THE CENTER PART OF THE REAR WINDOW AS IF THE DEFROSTER HAD STARTED A FIRE. I IMMEDIATELY TURNED THE REAR DEFROST OFF AND THE SMOKE CEASED. WITHIN A MATER OF SECONDS, THE RIGHT PANEL OF THE REAR WINDOW POPPED VERY LOUDLY AS IT SHATTERED, PRESUMABLY FROM THE FIRE. I WAS DRIVING ON A RURAL ROAD WHEN THIS OCCURRED. I DO HAVE A POWER REAR WINDOW ON THE VEHICLE AND THERE IS A RECALL ALREADY IN CANADA FOR CHEVROLET SILVERADO'S OF MY MODEL YEAR WITH THE REAR POWER WINDOW HAVING FIRES STARTED BY THE REAR DEFROSTER.