How to make circles with arrows?

Question

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.text,calc,arrows.meta}
\begin{document}
\begin{tikzpicture}
\coordinate (O) at (0,0);

\draw (O) circle (2.5);
\draw (O) circle (1.5);
\draw (O) circle (0.5);

\draw[decoration={text along path,reverse path,text align={align=center},text={ss}},decorate] (0.6,0) arc (0:180:0.6);
\draw[decoration={text along path,reverse path,text align={align=center},text={Nil }},decorate] (1.6,0) arc (0:180:1.6);
\draw[decoration={text along path,reverse path,text align={align=center},text={Nilnt}},decorate] (2.6,0) arc (0:180:2.6);



\end{tikzpicture}
\end{document}

Question: Instead of writing the text on the each circle, I want to write it outside the circle with an colored array pointing to it.

See the image given below which is what I want to draw.

Answer 1

Like this?

\documentclass[tikz,border=5mm]{standalone}
\usepackage{colortbl}
\usetikzlibrary{decorations.text,calc,arrows.meta}
\begin{document}
\begin{tikzpicture}
\coordinate (O) at (0,0);

\node at (O) [blue,draw,circle,minimum size=5cm] (circle3){};
\node at (O) [red,draw,circle,minimum size=3cm] (circle2){};
\node at (O) [draw,circle,minimum size=1cm] (circle1){};

\node[matrix,row sep=8mm] at (4,2) {
                    \node(Nilnt){\textcolor{blue}{Nilnt}};\\
                    \node(Nil){\textcolor{red}{Nil}}; \\
                    \node(ss){ss};\\
                };

\draw[<-,blue] (Nilnt)edge[bend right] (circle3.80) ;
\draw[<-,red] (Nil) edge[bend right] (circle2.60);
\draw[<-] (ss) edge[bend right] (circle1.20);
\end{tikzpicture}
\end{document}

Answer 2

I would probably let the arcs go out in tangential or orthogonal directions.

\documentclass[tikz,border=3.14mm]{standalone}
\begin{document}
\begin{tikzpicture}
\coordinate (O) at (0,0);

\draw[blue] (O) circle (2.5);
\draw[green!60!black] (O) circle (1.5);
\draw[red] (O) circle (0.5);

\draw[blue,-latex] (80:2.5) to[out=-10,in=180] (3,2.5) node[right] {Nilnt};
\draw[green!60!black,-latex] (80:1.5) to[out=-10,in=180] (3,1.5) node[right] {Nil};
\draw[red,-latex] (80:0.5) to[out=-10,in=180] (3,0.5) node[right] {ss};
\end{tikzpicture}
\end{document}