When gunpowder ignites it burns rapidly. What can be done to gunpowder to make it explode with greater force?
Reduce the particle size.
The rate of any chemical reaction is strongly affected by the size of the particles, as reducing this increases the area available for reactions to take place, assuming constant masses are compared.
A second option would be to confine it, or partially confine it, causing the gas pressure to rise substantially before being released.
Do hope you are not asking for nefarious purposes, just getting homework done ;-)