It depends on how complex life you want to have. For simplicity, I will refer to what we can observe on Earth.
The body of water with the highest salinity on Earth is Gaet'ale Pond
The water of Gaet'ale Pond has a salinity of 43%, making it the saltiest water body on Earth. The waters of the lake originate from a thermal spring located beneath it. For this reason its temperature (50–55 °C) is hotter than the environment.
No life forms are mentioned to be living there, while in the Don Juan Pond in Antartica, studies are equivocal.
Salinity varies over time from 200 to 474 g/L, dominated by calcium chloride, and is over 18 times the ocean's salinity and 1.3 times that of the Dead Sea. It is the only Antarctic hypersaline lake that almost never freezes with a salinity of 338 ‰ = 33.8%. It has been described as a groundwater discharge zone.
Lake Rebta, the third in the ranking, hosts complex life forms like fishes:
The lake is known for its high salt content, up to 40% in some areas, [...] Fish in the lake have adapted to its high salt content by evolving ways to pump out extra salt and keep their water levels balanced. The fish are approximately four times smaller than those living in a normal environment, as a result of salt water fish dwarfism.
Based on the above it seems reasonable that you can have some life forms at around 35% salinity.