This is your standard Limited Animation method of drawing an explosion: as a spikey ball. Usually several such, concentric and multi-colored. Expect some smoke too.
This effect can also be used to accentuate any heavy or significant impact, such as a blow to the head. See also Hit Flash.
In Real Life, of course, it's possible to achieve an explosion which simulates this effect. Only, usually, not [...] [tvtropes.org]