According to latest news from Rúv on recent survey on Bárðarbunga volcano the cauldrons that appeared during the Holuhraun eruption (2014 – 2015) continue to grow in size and there has been increase in hydrothermal output in those cauldrons. Distance between the cauldrons is 800 meters and their depth is more than 100 meters. In one of the cauldrons a hot spring has been observed and strong sulphur comes from it. The water in the cauldrons no longer freezes due to heat. Rock has also been exposed that have never been seen before and have been under the glacier for thousands of years.
Video of the cauldrons can be seen here on Rúv News report. Everything is in Icelandic.