Water with a considerable amount of added salt no longer boils or freezes at normal temperatures. In cooking, salt is used in such small increments that there is no good example to demonstrate how the addition of a lot of salt (like a cup) changes the boiling temperature of water. One demonstration of how salt does change things is hand-crank ice cream makers ... it depends on salt's effect on ice water. Water and rock salt surround the inner canister that holds the ice cream base. The mixture of water, salt and ice creates an iced brine solution that is well below freezing (around 10 to 20 degrees Fahrenheit) but yet it is still in liquid form. Without this process the ice cream base would never freeze. What a disappointment that would be. ~ Chef Wilkinson ~