Image on full slide with captions in beamer

Question

I followed this answer to put a picture on the full slide:

https://tex.stackexchange.com/a/333121/27523

{
\setbeamertemplate{navigation symbols}{}
\begin{frame}[plain]
    \makebox[\linewidth]{\includegraphics[width=\paperwidth]{kernel-panic.png}}
\end{frame}
}

Now, I would like to put some text onto the picture. I wrote

\begin{frame}[plain]{The problem}

but this pushed the picture down.

How can I make LaTeX to treat the picture as a background? So that I can write caption onto it.

Answer 1

Another answer for the quoted question gives a solution:

https://tex.stackexchange.com/a/248218/27523

{
\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{background canvas}{\includegraphics[height = \paperheight, 
                                  width = \paperwidth]{image.jpg}}
\begin{frame}[plain]
\end{frame}
}

And yes, as the name suggests, this sets the picture as a background canvas.