This refers not to boiling something in water but to the boiling point of heat, creating bubbles. At http://spaceweather.com (May 3rd 2019) we are informed the Sun is boiling – even though there have been no sun spots for 12 days. However, the surface of the Sun is covered with convection cells and the Sun is so hot it literally boils. Bumps on the surface are called granules – which are convection cells …
… Now, a sun spot is on the way. It has spent two weeks on the far side of the Sun and has now turned in our direction (see http://spaceweather.com 6th May 2019).
… and going back a couple of days to (2nd May 2019) the web site has an interesting story on geomagnetic jerks. Earth's magnetic field is inconstant and the magnetic north pole wanders across the Arctic. In addition, every 3 to 12 years Earth's magnetic field suddenly accelerates in one direction or the other. The most recent jerk was in 2017. In a research paper published in Nature Geoscience (22nd April 2019) which describes how they created a computer model for geomagnetic jerks based onthe physics of hydrodynamic waves in Earth's core. According to the model the jerks originate in rising blobs of metal that form deep inside the Earth. As they travel upwards the blobs disrupt the normal flow of magnetic field geometry currents, and in turn, cause jerks. On the other hand, being a model, one may wonder what is left out.