My informant told me that, when she was younger and had a sore throat her mother would make her gargle with warm salt water to get rid of it. She continues to pass down this method for curing a sore throat to her children.

Warm liquids generally tend to be soothing for the throat. Salt absorbs liquid and dries out areas, so if it absorbs liquid in the back of the throat it can help to kill the bacteria, which needs a wet environment to survive in.