AFAIK, efflorescence is caused by moisture pushing through masonry from the other side, or wicking into it from somewhere, usually the ground. If you remove the deposits and seal the wall, you'll just trap the moisture inside. That's probably not what you want to do.

Or am I misunderstanding your situation and/or question? Maybe the efflorescence is appearing on the inside of a wall that's painted on the outside?

Some photos would probably help.

Thank you, DavidR!

To clarify, this is a free-standing courtyard wall in southern Arizona. If sealing isn’t a good idea, perhaps the only thing I can do is hose it off well when it occurs, as there may be no way to prevent it. This happened after a very atypical storm which left over a foot of snow. I once tried using a dilute vinegar solution which ate through the paint.