Baking soda and vinegar, both being common household items, are ideal for any wannabe bomber.
Baking soda = A versatile raising agent.
Vingegar = A common, strongly acidic substance.
By filling an empty bottle with about an inch of baking soda and the rest with malt vingar until the mixture turns slightly brown will be the right ratio; thus making a harmful and simple bomb.
Some may need a dash at a hard floor to explode and will be propelled along a large distance.