Boom slimes are often heard before they're seen. The slime cells of a boom slime are constantly vibrating, causing their slime to increasingly crackle with energy before ultimately exploding. However, the boom slime always comes out unscathed, though always a little dazed.
Boom slimes are constantly building toward an inevitable explosion, making them quite hazardous to ranchers. In addition to those explosions causing bodily harm, they also have the capacity to send all nearby slimes flying into the air, making them a hard slime to corral.
Highly volatile boom plorts have all sorts of applications, including powering rocket thrusters and demolitions. Military organizations value their highly destructive capabilities for 'medical technology and other research'. Imagine that!