Original Source: Taizyd Korambayil

This is a neat material where you take a pre-fragmented mesh (created in any 3D authoring tool), store the pivot locations of each fragmented piece to the UV channels (3 channels total). Then you drive the fragmentation using an expanding mask as seen in the material below.

Tip: You must store pivot locations for each fragmented piece in separate UV channels (each channel representing the X, Y, and Z axis).

What it looks like; notice there is no/minimal light bleeding between fragments prior to them breaking up.

The material in Unreal Engine 4.