TRUCK CAUGHT FIRE WHILE DRIVING ON HIGHWAY. NO WARNING SIGNS ON DASH. STARTED TO SLOW DOWN THEN SMOKE STARTED COMING FROM FRONT OF HOOD AS IF OVERHEATING. I PULLED OVER TO EMERGENCY LANE, TURNED CAR OFF , THEN POPPING SOUND CAUSING TRUCK TO GO INTO FLAMES AND POPPING WITH BIG EXPLOSION AND BURNING RAPIDLY. I WAS ABLE TO GET OUT BECAUSE I HAD DOOR ALREADY CRACKED OPEN AND RAN AWAY FROM VEHICLE.