for snare you can get it to explode by compressing the reverb return with the snare track, with some fiddling with the attack and release you can get the verb to kick up after the intial snare hit...finding the right release time is crucial, the attack should be damn fast as to not 'give away' the explosion.
I usually resort to using the predelay parameter on the reverb unit to achieve this "explosion" effect.
I'm sure there are many uses for sidechaining reverb return compression but that's what comes to mind...someone please enlighten all of us to some other techniques.