What happens if you cast a shrink spell on an ogre then lure it to a very narrow tunnel then dispelling first spell and casting enlargement? Does that ogre explode? deforms? just gets stuck? or nothing at all?
Assuming you're talking about reduce and enlarge person, consider this part of the second spell:
Technically the rules are silent on whether you could crush a creature by removing reduce person, but unless they were already squeezing through a small space, there's no way they'd be crushed anyway.