A Big Boom is the unstable version of a Big Bang when the (possibly) expanding bubble protecting the things inside the universe breaks and the particles are scattered across whatever void that Universe was forming in.
Force[]
The power of this explosion can potentially knock away surrounding universes and sometimes even obliterating them as a whole, but the chance of a Big Boom happening is quite rare in terms of multiversal properties. There are even multiverses where only big booms happen or are not possible at all.
Remnants[]
The scattered particles from the explosion, being only quarks, since there's no bubble for the particles to fuse in and the force from the explosion scatters each particle far away from each other. These particles either evaporate due to the weak fabric of time in the Interdimensional Void, making them live for a short time, or are absorbed into expanding or already living universes.