One scientific suggestion is that there may have been a cosmic airburst caused by a large meteor exploding in the air above the cities.
The enormous heat generated by the explosion could explain the destruction of the cities, but that doesn't explain the numerous balls of elemental sulphur discovered, since the sulphur in meteors is only about 6% by weight and is usually in the form of sulphur compounds.
Unless there's evidence of meteors of pure sulphur floating around in space, a better explanation is that God engineered a midair explosion of a large rock of elemental sulphur above the two cities and the fragments melted into balls and ignited as they fell on the cities.
