IT WAS EARLY IN THE MORNING (0430), I GOT CALLED INTO WORK, THE WINOWS IN THE TRUCK WERE FOGGED UP, SO I TURNEDON MY REAR WINDOW DE-FROSTER AND FRONT WINDOW DE-FROSTER. AS I TURNED THE CORNER OUT OF NEIGHBORHOOD (LESS THAN 1/2 MILE) I HEARD A LOUD BANG AND I THOUGHT I HIT SOMETHING. I STOPPED THE TRUCK AND GOT OUT TO INSPECT IT, AFTER SEEING THERE WAS NO DAMAGE TO THE BODY I LOOKED UP AND SAW A LARGE HOLE IN MY DRIVER'S SIDE REAR WINDOW THE SIZE OF A GRAPEFRUIT. AS I WAS INSPECTING THE WINDOW I TOUCHED THE LOWER LEFT CORNER AND BURNDED MY FINGER. IT WAS LIKE TOUCHING A LIGHT BULB THAT IS ON. I IMMEDIATELY TURNED THE DE-FROSTER OFF AND CHECKED THE PASSENGER SIDE REAR WINDOW AND IT WAS AT A NORMAL TEMPERATURE.