It's the body's natural reaction to detecting a toxin and involves the chemoreceptor trigger zone (CTZ), which plays a vital role in identifying harmful substances in your blood and cerebrospinal fluid. When the CTZ detects these toxins, it sends signals to trigger the vomiting reflex (emesis). Located in the medulla oblongata, the CTZ has different receptors that each serve specific functions in this process. Irritation in the gastrointestinal (GI) tract can also lead to the releasing of both dopamine and serotonin, with dopamine typically being released in larger quantities. This is why targeting the dopamine D2 receptor is important with SN, particularly since antagonists at this receptor can more importantly aid in gastric emptying, moving contents from the stomach to the small intestine more quickly for absorption. Even more important for SN purposes is this prokinetic effect over its actual anti-nausea properties.
I suppose some may due to the saltiness itself, but more so for the reason described above.
With whatever you decide, I hope you find everything you are looking for and get peace & serenity.