Adding a non-volatile solute like salt to water elevates its boiling point and depresses its freezing point as a standard colligative property.
The claim is a well-established physical law (boiling point elevation, a colligative property) that does not require citation as it is a fundamental piece of common scientific knowledge. None of the retrieved papers specifically target or measure the boiling point elevation of saltwater, leaving the index lists empty while confirming the verdict.