into thin air
(idiomatic) Immediately and inexplicably out of sight.
He seemed to vanish into thin air.
...the more accurate the calculations became, the more the concepts tended to vanish into thin air. Robert S. Mulliken
I've found that worry and irritation vanish into thin air the moment I open my mind to the many blessings I possess. Dale Carnegie
They too, like so much that to the common eye seems solid, may melt into air, into thin air. James Frazer
The world starts to exist, for Americans, when we are in conflict with a place. And then all of a sudden, Afghanistan pops up on the TV screen and it becomes a place. And it exists for three weeks, and then it disappears into thin air. Isabel Allende
Accounts claim an apparition says, "What you're looking for is over there," before vanishing into thin air. Source: Internet
And the president’s radical austerity, along with the widespread suspicion that some of the previous administrations’ big budgets disappeared into thin air? Source: Internet