A "burst of fire" is a sudden, intense burst of flames, and there are several synonyms that can be used to describe it. One alternative is "flame burst," which highlights the explosive nature of the fire. "Blaze" is another option that connotes a strong, bright flame. "Inferno" adds a degree of danger and chaos, often associated with uncontrollable fires. "Volleys" is a military term that can be used to describe a series of rapid, successive bursts of gunfire or explosions. Finally, "conflagration" is a more formal and dramatic term that describes a large and destructive fire. All of these synonyms can add variety and depth to descriptions of fires and flames.