Most of Tolkien's orc-names are simply meaningless, but there is a slight possibility that Bolg's name derives from Old English. The word gebolgen in that language comes from the verb 'to be made angry', and indeed that exactly describes Bolg's role in the story of the The Hobbit.
In an early name-list given in volume 4 of The History of Middle-earth, 'Bolgen' is given as an Old English name for Melkor, using the same verbal root. It's clear, therefore, that Tolkien had already considered this as a name for an evil being, so there's at least a possibility that Bolg inherited his name from this source.
Another possibility is that the name comes from an early example of Tolkien's invented languages, known as Mágol or Old Mágo. That language was by no means as developed as the better known Elvish tongues, but it is known that Tolkien at least considered using it as the Orkish language, and that it contained a word bolg that meant 'strong'.