echo 'You\'re doing it wrong' # unclosed single quote

echo 'You'\''re doing it wrong'
echo $'You\'re doing it wrong' # ksh/bash/zsh "c-style" quote

In POSIX shell, the shell cares about nothing but another single quote to terminate the quoted segment. Not even backslashes are interpreted.

POSIX.1 Shell Command Language § 2.2.2 Single Quotes:

Enclosing characters in single-quotes ( '' ) shall preserve the literal value of each character within the single-quotes. A single-quote cannot occur within single-quotes.