how to use '{' with variables in string (PHP)

Question

I want to output a string like this "{$myvar}" but it doesn't work. if for example $var = 1;

    echo "$var";     // output "1"
    echo "{$var}";   // output "1"
    echo "\{$var\}"; // output "\{1\}"

how do I get "{1}" as a result ???

thanks