Usage of 'until'

[Daemon99]

Add the eggs and beat until frothy.

I have picked this line from Oxford Dictionary. What is a bit puzzling here is the usage of the adjective right after until. Is that a common usage? Can someone please tell me if the following sentence is correct?

Walk up the hill until tired. (would it mean until hill is tired?)

Can someone please provide similar examples?
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Non-native speaker of English
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I intend to live forever - so far, so good.

[Alan]

Hi Daemon,

This construction only works if it is clear which is the subject of both parts. Add the eggs and beat until frothy= You add the eggs and you beat (them) until (they are) frothy. Walk up the hill until tired = You walk up the hill until (you are) tired. I agree from what you indicate that this is a construction that is open to ambiguity. I would suggest that it is a 'lazy' construction and it is better to write the sentence out in full. If it is used, it is usually reserved for instructions that you would get with a package telling you how to make/ assemble something as in: Hold the two pieces of wood together until (they are) straight - Glue part A to part B and leave until (they are) firm.

Alan
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English as a Second Language
You can read my ESL story Present Simple