A word that means to depart suddenly is "plump" or "plumped"
abruptly, unexpectedly
Abruptly.
a flinch
This could be bolt.
She was driving down the street, but then suddenly, out of nowhere, another car ran a stop light and T-boned her.
Grasp or seize.
Although it has the actual mean of "sudden", the word is abrupt.
"Suddenly" is an adverb.
Sprout would be a word for 'to shoot up suddenly'.
No, "suddenly" is not a compound word. It is an adverb formed from the adjective "sudden."
Suddenly is an adverb and its comparative is formed by putting the word "more" in front of it.
The word that means to draw back suddenly is "recoil."