A small amount of potassium chlorate(V) is placed in a Pyrex boiling tube.
The tube is clamped at a slight angle to the vertical and the potassium chlorate(V) is heated until it melts.
The demonstrator then drops a jelly baby into the melt.
The sugar in the jelly baby reacts vigorously with the potassium chlorate, burning with a lilac flame and lots of vapour is ejected making a roaring sound – the ‘scream’.