Bombfire, is a variant of bonfire. Although both words mean a fire created for enjoyment, for example on Guy Fawkes night, the
etymology is different.
A bombfire got its name from being created on an open vacant lot by
the community. These lots were called a bombie, or bomb site. As a hold over from
World War 2, when I'm the UK many building were destroyed from bomb attack
It took several decades for all of these lots to be built on again. Empty lots continued to be called bomb sites, and fires on these sites, called bomb fired.