Two-column beamer ToC with control over the breaking point

Apparently, \addtocontents also works with the beamer class. Use \newpage (not \clearpage!) to force a column break.

\documentclass{beamer}

\usepackage{multicol}

\begin{document}

\begin{frame}{\contentsname}
\begin{multicols}{2}
\tableofcontents
\end{multicols}
\end{frame}

\section{bla}
\begin{frame}{bla}
Some text.
\end{frame}

\section{blubb}
\begin{frame}{blubb}
Some text.
\end{frame}

\section{foo}
\begin{frame}{foo}
Some text.
\end{frame}

\addtocontents{toc}{\newpage}

\section{bar}
\begin{frame}{bar}
Some text.
\end{frame}

\end{document}

An excellent solution has been posted here:

https://tex.stackexchange.com/a/136082/113639

\begin{frame}
    \frametitle{Outline}
    \begin{columns}[t]
        \begin{column}{.5\textwidth}
            \tableofcontents[sections={1-3}]
        \end{column}
        \begin{column}{.5\textwidth}
            \tableofcontents[sections={4-5}]
        \end{column}
    \end{columns}
\end{frame}

As you can see, the break points are manual here (using the sections= parameter). Furthermore, this solution avoids all the vertical alignment problems of the other multicols solutions I have seen here so far, where the second column would often not start at the top.