&quot;Boiling vessels&quot; have been a key component of most UK armoured vehicles since late in WW2:<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Boiling_vessel" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Boiling_vessel</a>