Making Juice Out of a Concentrate

When Rafi woke up from his Shabbos afternoon nap he decided to make for himself a cup of apple juice from a concentrate. After he poured a little bit of the concentrate into a cup and was about to add water to it when his sister Shaina asked, “Are you allowed to do that on Shabbos?!”

“Why not?” asked Rafi.

“Well you are making juice from something that cannot be drunk by itself. That sounds like the melacha of Makkeh Bepatish!” explained Shaina.

“Hmm...good point. Never thought of that,” replied Rafi.

Question: Can Rafi make the juice from the concentrate?