out of thin air
out of nothing
from nowhere

Many people have heard music and felt cold air from nowhere.

The words came clearly to me, from nowhere, without thought.

The two of them seemed to have appeared from nowhere.

You just don't come from nowhere and go to the Senate.

Then a man's face suddenly appeared from nowhere in front of my eyes.

Her voice had come from nowhere during a break in the music.

It came to him from nowhere at all, out of the blue.

"And it came from nowhere over the last five years."

But when you are coming from nowhere it is a real start.

The question seemed to have come into his mind from nowhere.