A burst of dark side energy occasionally occurred when a powerful Sith or Dark Jedi was killed. The resulting shockwave was sometimes very powerful, other times it was a simple dissolving of physical matter.
Joruus C'baoth's death burst
The first known sighting of these occurrence was in 3951 BBY, when the remains of Darth Nihilus were consumed by a small burst of scarlet energy after his death at the hands of Meetra Surik.
In 3637 BB, the Immortal Emperor known as Valkorion exploded in a burst of Dark Side energy, however, Valkorion's body remained behind.
Later, in 3630 BBY, in the mind of the Outlander, Valkorion's spirit exploded into a burst of Dark Side energy after getting himself killed by the Outlander.
Shortly after Palpatine won the chancellorship, Darth Plagueis released such a phenomenon upon being electrocuted by Palpatine after the latter fed him enough wine to make him lose consciousness. The burst was powerful enough to send ripples throughout the Force, strong enough to be felt throughout Coruscant. However, unlike other Sith Lords who faced this phenomenon, Plagueis`s body remained
In the year 19.5 BBY, Nikkos Tyris and the other Jensaarai leader's deaths created a dark side burst.
In the year 3 BBY, Shaak Ti released a similar burst after deliberately falling into the Ancient Abyss upon losing her duel to Galen Marek, though she stands out in that she was never a dark-sider whatsoever. Shortly thereafter, Marek apparently released a dark side burst when he sacrificed himself in his battle against Darth Sidious, although his body was left behind (and it happened after he abandoned the dark side). Six years later, Sidious released a massive surge of blue dark side energy after being thrown down a reactor core shaft aboard the second Death Star. Later on the planet Ruusan, Jerec's body dissipated after he was killed by Kyle Katarn. In 8 ABY, the Nightsister Ocheron gave off a burst of dark energy after being beheaded by Luke Skywalker. One year later, at 9 ABY, Joruus C'baoth also released a blast of energy after being killed by Mara Jade with Leia's lightsaber, blowing a gaping hole in the side of Mount Tantiss.
Darth Traya appears to release a dark side burst in the video game Star Wars: Knights of the Old Republic II: The Sith Lords, when the Exile throws her off of Trayus Core into a bottomless pit. It is unknown though if it was Traya releasing Dark Side energy or not, as it could have simply been her body being fed to the core of dark power on Malachor V. Regardless, this only occurs in the dark side ending of the game and is therefore not a canonical event.
Even though the Jedi Master Shaak Ti was in no way a practitioner of the Dark Side, the manner in which she died in the Sarlacc pit was noticeably similar to the dark side burst, possibly implying that it happens due to the power level of the force user and not due to force alignment.
- Book of Sith: Secrets from the Dark Side