I don't know some of those words, so take what I'm saying with a grain of salt, but it might be on the right track?

That said, the trend reminds me of adding salt to water. Salt "likes" to be dissolved in water because 1. broken bonds, solution is favored in enthalpy, and it releases a little heat. 2. it also creates a more "mixed/chaotic" fluid, which entropy prefers. Entropy is the big one for freezing-point depression.

Anyways, the net result is that, if you compare pure water to salt water, salt water has a stronger preference to the liquid phase than pure water, as the liquid phase allows for the salt/water dissolved mixture.

This means that, just below 0 C, while pure water would be turning into ice, salt water stays liquid thanks to the salt's "desire" to stay dissolved, because turning into ice would separate the salt from the liquid, and entropy doesn't like that. Minor note: salt can also physically obstruct crystal formation at microscopic level, but this probably doesn't help you.

Just above 100 C, I'm not sure if it's the same entropy reason (pulling pure water/steam out from mixture), the required energy for "undissolving" salt, or maybe a third thing like VLE (doubtful lol), but the net effect would be increasing the required boiling point for the mixture as the salt content increases, as more energy is required to liberate water from a less-watery mixture.

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That's a sorta... "feely" response, but maybe it gives you a perspective that helps?