Rice can almost fully disintegrate if left in water, and will become something that disintegrates even more if stirred or agitated. In many other applications it replaces a pleasantly tactile and textured starch with a sort of sludge slurry, but as is often the case if you know and expect this it can be used in some applications advantageously. Thickening a stew is one of them. It's actually my favorite stew thickener. We discovered this the hard way once, though. We just "threw some rice" into a stew, and, well, if you put enough "sludge slurry" into a stew it starts to dominate... since then, though, it's been something very useful, especially since I'm allergic to flour, one of the traditional choices.