Sure.
How is it "reached", typed in or calculated from a formula ?
Why do you want a popup, is the cell outside the visible area ? If not then
a color change may be a less annoying solution.
Do you want a popup that has to be OK'ed away ?

Best wishes Harald

"Israeli Ann" <Israeli skrev i melding
...
Can I be notified (e.g. pop up) when a certain level is reached in a cell