I see nothing wrong with sokarul's test. Perhapse you could do a better one. Actually, I just did one myself, and anybody here can.
Get a syringe, weigh it.
fill it with a little bit of water. Weigh it again.
Cover the end of the syringe, and pull the stopper to the end, creating a near-vacuum, use a screw or something similar to lock the stopper at the end.
Weigh it again. According to sceptimatic, the liquid inside should be near weightless, so it should weigh the same as when it was empty, but surprise, it doesn't.
Proving that vacuums don't make objects weightless.