As well as the flour bomb, use a long piece of very wide bore glass tubing with a fine piece of fine copper mesh shaped and placed in one end. Place a teaspoon of flour down the tube to rest on the mesh. Aim into a blue bunsen flame and blow down tube to blow flour out of mesh. Should result in a large fireball!

Safety Precautions
Sound fairly dangerous. Would the original author or someone who has done this demo add some safety precautions please.

Flour mills have been destroyed when a flour-air mixture ignited explosively. While flour is difficult to burn on its own, when it is turned into a dust cloud in the presence of a flame it will combust rapidly due to the large reactive surface area that is exposed. Similar reactions can occur with a number of other fine combustible powders. e.g. sawdust, coal dust, grain dust (in grain elevators) and some metal powders.