Just a quick setup I did while waiting for some simulations to finish, but it's kinda cool and you could of course build a bit more fancy system for activate the pieces, like activating the inner ones only after outer ones are activated or if you set a bias so higher pieces will be activated before lower ones - or you could use the alive attribute to remap piece color instead of the sice after it's activated, etc... There's lots of fun stuff you could do. :)
Scene file: www.bit.ly/ff_POP_cubular_dissolve