The tour manager occasionally popped his head in, but didn't interrupt.

But that didn't stop people in security from occasionally popping their heads in and having a look around.

Some tentative nature-of-space theories imagine empty vacuum to be a seething sea of almost-there particles which occasionally pop through the "surface" into existence.

He had a fire going in the old iron cookstove: a wood fire, from the way it popped occasionally and from some wisps of pungent smoke.

The negotiation is conducted at the keyboard, with Ripka answering as well as asking questions, and Joe occasionally popping in with advice.

Glimmers of his laid-back country comic style occasionally pop through the paint-by-numbers dialogue.

Since then, Mitoto would be occasionally popping into Seina's life from time-to-time, often helping him out during certain events in the boy's life.

Over the next decade, Vukota forged a reputation as a tough scrapper and punishing forechecker who could occasionally pop in a goal.

Others pop in only occasionally, for nostalgia's sake.