 Metal chlorates decompose to give the metal chloride an oxygen gas. If we heat potassium chlorate, the potassium chlorate first melts and then starts to decompose. The bubbling that appears is the formation of oxygen gas. The oxygen gas escapes from the tube, leaving the metal chloride behind. If we bring in a glowing splint, the glowing splint will burst into flames due to the increased rate of combustion due to the presence of the oxygen.