Liquid at Tables?

Hi all! I was recently in Korea this last April with my boyfriend and there's something I haven't stopped thinking about. We went to a few places to eat where they had the kettles with what we thought was water at the tables. So like normal, we poured some into our cups and me being the water-holic i am, I went to drink it first. At some of the restaurants it was plain normal water, but at 2 or 3 of the places, it wasn't. It was a yellowish color and i think it almost had a popcorn-like taste, i would ask my boyfriend what he thought it tasted like but he refused to drink any and made me taste all of our water first before he drank. I tried looking up on Google what this was, but I couldn't find an answer, do any of you know? I would include pics of what it looked like but they were in metal cups and the camera didnt quite pick up the color