Why aren't they simply boiling the water, nuclear powered? That article says membrane desal leaves half the water extra salty, is that right? Does boiling it le

Why aren't they simply boiling the water, nuclear powered? That article says membrane desal leaves half the water extra salty, is that right? Does boiling it leave that much? I'd imagine there'd just be a concentrated, mostly-solid byproduct. I'm probably wrong else everyone would already be doing this. OTOH, many people and places seem to be going against nuclear power, so perhaps it isn't just a technical issue. At any rate, that article just left more questions than answers.