Yes. You can mix salt and water; three parts water to 1 part salt. You can also add vinegar for a better effect. The best time to apply is when there's no imminent rain to wash it off, and the weather is very dry as weeds will be already under stress due to lack of water.
Salty water is effective against young seedlings, but it'll need to be repeatedly applied to more mature plants with more developed root systems. It's not effective against deep-rooted perennials such as dandelions. Salt can damage your soil, killing microorganisms and worms and binding to minerals in the soil, so you need to take this into account if you're going to be growing flowers and vegetables in the future. On paths and driveways, this is unlikely to be a concern.