The explosion as Palpatine died
On occasion, when a formidable Sith or Dark Jedi met their death, a violent emanation of dark side energy would erupt. This resulting wave of force could range from a simple disintegration of the body to a powerful shockwave.
Back in 3951 BBY, the first recorded instance of this phenomenon occurred. The remains of Darth Nihilus were engulfed in a small, scarlet burst of energy following his death at the hands of Meetra Surik.
In 3637 BB, the being known as Valkorion, the Immortal Emperor, detonated in a surge of Dark Side energy, yet his physical form remained intact.
Subsequently, in 3630 BBY, within the mind of the Outlander, Valkorion's spirit was destroyed, resulting in an explosion of Dark Side energy after the Outlander killed him.
Not long after Palpatine assumed the role of chancellor, Darth Plagueis unleashed a similar event. This happened after Palpatine electrocuted him, having plied him with enough wine to render him unconscious. The resulting burst was so intense that it sent ripples through the Force, felt across Coruscant. However, unlike other Sith Lords who faced this phenomenon, Plagueis's corpse remained
In 19.5 BBY, the deaths of Nikkos Tyris and the other leaders of the Jensaarai triggered a burst of dark side energy.
During 3 BBY, Shaak Ti generated a comparable burst. This occurred when she intentionally plunged into the Ancient Abyss after losing her duel against Galen Marek. She is unique in that she was never aligned with the dark side. Shortly after, Marek seemingly created a dark side burst when he gave his life fighting Darth Sidious, although his body was preserved (and this happened after he turned away from the dark side). Six years later, Sidious unleashed a powerful wave of blue dark side energy after being cast into the reactor core of the second Death Star. Later, on Ruusan, Jerec's body vanished after Kyle Katarn killed him. In 8 ABY, the Nightsister Ocheron emitted a burst of dark energy upon being decapitated by Luke Skywalker. A year later, in 9 ABY, Joruus C'baoth also discharged a blast of energy after Mara Jade killed him with Leia's lightsaber, creating a large hole in Mount Tantiss.
Darth Traya seems 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 from Trayus Core into a pit with no bottom. It is not certain if Traya released Dark Side energy, or if her body was simply consumed by the dark power at the core of Malachor V. This only occurs in the dark side ending of the game, making it non-canonical.
Even though Jedi Master Shaak Ti never practiced the Dark Side, her death in the Sarlacc pit resembled a dark side burst, suggesting that the phenomenon is tied to the force user's power level, regardless of their alignment.