  The pioneering work of William F. Vinen (also known as Joe Vinen) on thermal
counterflow turbulence in superfluid helium-4 largely inaugurated the research
on quantum turbulence. But despite decades of research on this topic, there are
still open questions remaining to be solved. One such question is related to
the anomalous increase of the vortex-line density $L(t)$ during the decay of
counterflow turbulence, which is often termed as the ``bump'' on the $L(t)$
curve. In 2016, Vinen and colleagues developed a theoretical model to explain
this puzzling phenomenon (JETP Letters, \textbf{103}, 648-652 (2016)). However,
he realized in the last a few years of his life that this theory must be at
least inadequate. In remembrance of Joe, we discuss in this paper his latest
thoughts on counterflow turbulence and its decay. We also briefly outline our
recent experimental and numerical work on this topic.
