The shrapnel usually flies out in all directions, at speeds approaching that of light -- but sometimes, the exploded bits do something different. They fly away from each other but in an orderly fashion, correlated with each other. This has been seen before in proton-proton collisions, and also in collisions between the nuclei of heavy metals like lead. In the heavy ion collisions, this correlation makes some sense, because physicists think it's the result of something called a quark-gluon plasma. This roiling soup of particles is the same primordial soup that existed for the first few millionths of a second after the Big Bang. The soup gathers particles together and pushes them in the same direction. Similarly, in proton-proton collisions, the particles are thought to be swept up in something called a color-glass condensate, which also behaves like a wave of gluons.