This slow motion video explains an phenomenon called "buckling instability" - the crimped edges of a splash of water. More importantly, it shows us how much familiar physics we don't notice until it's pointed out to us.
Every person reading this has been observing splashes ever since they first mustered enough coordination to throw a rock at a pool. We've all certainly seen how round object create a little crown of water and how splashing water develops crimps and ridges, but it takes something like this to make us really take notice. This video comes from the BYU Splash Lab, and shows us how low air pressure, high surface tension, and a number of other forces affect the splashes and the crimps.
During the video we learn that a sign of imminent collapse is the crimps in the water, known as "buckling instability." The crimps are drawn inward and and down until they form bags, which eventually cause the crown to round into a dome, and the dome to collapse. We also learn that less air pressure means less air drag, which means the crown doesn't collapse in on itself as quickly in a vacuum.
Check it out! It's beautiful, and it will teach you something about a phenomenon that's familiar, and that is even more interesting when explained.
[Sources: BYU Splash Lab]