Don Juan Pond may not freeze, but it does evaporate...sometimes completely. It appears to be replenished by a brine spring associated with a basaltic acquifer.
Because of the thin, dry atmosphere on Mars, evaporation rates are far faster. Without a subsurface source of liquid water, any pond on the surface of Mars, briney or not, would rapidy evaporate - far faster than any similar briney pond found on earth.
Its fun to speculate about potential comparisons from terrestrial examples. But that's all it is, speculation. At the current moment, we have no reason to believe that we will find similar Don Juan Ponds on Mars. Perhaps they are there, perhaps not. But given how rare they are in Antarctica, we have no reason to believe that they would be any less rare on Mars.
Once again, inferring that parts of Mars are wetter than Antarctica is really inaccurate. At the present time we don't know if Mars is wet at all...as I stated we've not yet found a single drop of liquid water on Mars. Its entirely possible we will not.
Space/Science » in reply to The post itself explains the terminology.
Don Juan Pond