Rashi on Exodus
מתלקחת בתוך הברד [AND FIRE] FLASHING UP AMIDST THE HAIL — a miracle within a miracle! Fire and hail mingled, although hail is water! But in order to perform the will of their Creator they made peace one with the other (Exodus Rabbah 12:4).
Sforno on Exodus
ואש מתלקחת בתוך הברד. Driven by the immense velocity and pressure of the descending hailstones. The heat generated in the atmosphere resulted in unnatural sounds being heard everywhere. Both hard and soft plants were destroyed by the hail. Verse 25 spells all this out in detail.
Or HaChaim on Exodus
ויהי ברד ואש, there was hail and fire simultaneously, etc. The word מתלקחת is used to inform us that though water and fires are opposites, one of which is bound to prevail over the other in any encounter, in this instance they demonstrated the ability to co-exist. This was possible since both were performing G'd's will by so doing.