bubble on the surface of water
Literal meaning: a bubble floating on water. Used descriptively, not idiomatically.
Bubbles are floating on the surface of the pond.
coming to nothing; something short-lived
Idiomatic use: efforts, plans, or hopes that vanish without result, like a bubble bursting. Often used in the pattern 水の泡になる (come to nothing). Sense 3 (something short-lived) is a less common extension of this metaphor.
Years of effort came to nothing.
His dream vanished in an instant like a bubble.