In this demonstration a piece of clay (or clay-like material) is squashed under a press. The lump of clay initially spreads out under the ram of the press. But once it reaches the edge of the ram instead of continuing to expand outwards it instead rises UP and seems to 'hug' the sides of the ram.
Why does it behave this way?
It reminds me somewhat of surface tension in liquids but since its a solid material (though 'flowable' to some extent) I'm not sure that is really the explanation.
The sample just about to be pressed:
(The video was obviously meant just to be entertainment, not any sort of real experiment, but I think its interesting nonetheless to see the effects of common materials subjected to uncommon situations. Sometimes these examples don't match one's intuition or expectations, a good opportunity to learn something.)