there are three main types of warheads for an RPG, the infantry (HE), armor (HEAT) and specialized.
HE works the same as a regular grenade...with a rocket on the back. it makes a moderate explosion and throws shrapnel all over the place.
The HEAT (most common, since they are mostly used against tanks) explodes forward, shooting molten copper or other similar metal, forward in a small line, this is hot enough to penetrate medium/weak armor and fill the tank with molten metal, killing the crew. Most modern tanks are pretty strong against these sort of attacks anyway, this (new system in the topic) is an added benefit.
The final, specialized, just shoot phosphorous, smoke, tear gas etc... The newest form is a fuel air bomb. They are used for everything from illumination and riot control to taking out bunkers and tanks formations.
All said and done, you really wouldn't take out the rocket portion of the RPG, since the infantry make to small an explosion, and the armor explode forward anyway. Since all the explosives are only in the small portion of the head, the rest is fuel for flight.