A Naquadah bomb is an explosive device of Goa'uld origin.
It uses Naquadah as fuel for the explosion. They came in a variety of sizes and shapes some taking on the form of chests while others were more spherical in form while others simply consisted of bars of naquadah.
The Goa'uld Nirrti used one such bomb and planted it in Cassandra. It collected the particles of naquadah, to form a round and intricately "carved" bomb. Its trigger system relied on a chemical interaction with potassium. A former test showed that microscopic particles of both elements coming into contact could cause enough damage inside a room up to the point of cut off the video of a security camera installed in a corner. The final chemical bomb would be a million times more powerful. A notable feature about the bomb is that it worked in proximity to a Stargate, which triggered the agglomeration of naquadah inside Cassandra's body. (SG1: "Singularity")
Impostor Imhotep (posing as K'tano) used small bars of naquadah which he lodged into small devices strapped onto the torsos of loyal Jaffa, who were chosen for kamikaze bombing operations against other System Lords' assets. (SG1: "The Warrior")
Goa'uld also used to booby-trap small chests, such as the one once owned by Sekhmet, capable of leveling Los Angeles' Orange County, while a similar one was found in a museum on an alien planet, and used to power up the local Stargate. (SG1: "Resurrection", "Bad Guys")
Ba'al intended to use a spherical naquadah bomb to destroy the Achilles in his time travel attempt at preventing the formation of Stargate Command. Strangely enough the bomb exploded with the strength of a depth charge. It's possible Ba'al chose a charge that would destroy the ship without damaging the Stargate on board. (SG1: "Continuum")
More powerful bombs, likely akin to nuclear warheads, could be found onboard Ha'taks. One of these was used by SG-1 in an attempt to destroy a Ori warship by transporting it through the transportation rings. However, this failed to worked. (SG1: "Flesh and Blood")